Power Module for Low Voltage DC Hybrid Circuit Breaker

This paper presents design and development of a power module used in a low voltage DC hybrid circuit breaker (HCB). The novel power module is rated for 125 A / 380 V and can interrupt electrical faults within approximately 300 μs in a power grid with up to 20 kA short-circuit capacity. The designed module employs an auxiliary power electronics switch including 30 V silicon MOSFETs with very low on-state resistance in series with an innovative high-speed and low ohmic mechanical switch. This enables completely arc-free switching. A main power electronics switch consisting of bare-die 1.2 kV IGBTs and SiC Merged PIN Schottky diodes is used for current interruption. These components characterized in previous publications are attached on an Al 2 O 3 substrate in such a way that the smallest possible inductive loss from current commutation loop and a reduced footprint are obtained. Additionally, a galvanic separation relay and integrated current measurement shunts are included. Finally, the substrate is placed on a Cu baseplate and encapsulated in both soft and hard encapsulations similar to standard power IGBT modules. Experimental results on fault current commutation and interruption, minimum required air gap for the mechanical switch, and steady state thermal characteristics are reported here. The findings enable the realization of the most compact and reliable HCB with the highest available power density currently feasible.